Discover and read the best of Twitter Threads about #CAfire

Most recents (24)

First, some good news: NorCal seems to have made through initial (extreme wind) phase of this critical fire weather event relatively unscathed. Few new small fires, but nothing unmanageable. A few thoughts as to why this was the case: #CAwx #CAfire
Very strong to extreme winds and exceptionally low humidity did materialize, despite an initial delay. A peak Bay Area gust of 89mph (with fairly widespread gusts above 50-60 mph), and peak Sierra Nevada gusts well over 100mph, were recorded. #CAwx #CAfire
In some spots, extreme winds did indeed mix down to low elevations (interior North Bay Valleys; Oakland Airport; San Francisco; Half Moon Bay). But some locations closer to sea level saw little wind,so sea level gusts were somewhat less widespread than initially anticipated.#CAwx
Read 6 tweets
Folks: major wind/extreme low humidity/fire weather event is still coming--it just might be slightly delayed (by a couple hours or so in SF Bay Area). Very surprised to hear that PG&E is cancelling some of the planned PSPS with strong winds still inbound?? #CAwx #CAfire
Are @NWSBayArea or @NWSSacramento aware of any major forecast changes that would explain why PG&E is claiming that conditions will no longer justify a PSPS (at least in portions of East Bay Hills and Sierra foothills)? I certainly am not...
cc @RobMayeda @psuweatherman I am genuinely baffled here.
Read 4 tweets
Confidence increases regarding a significant offshore flow event late in the weekend - not just strong winds, but the very dry airmass with it. Comparing offshore gradients SFO-WMC. (1/4)
2017 Wine Country Fires -17.8mb
2019 Kincade -16.3mb
2020 Model Fcst Sunday night -18 -20mb
Regarding the model forecast - I've seen this before where the models put out -20mb, but verify closer to the upper teens. That was the case 2017. Here's a look at the wind anomaly - wish there was a 925 mb layer as that is a key level for the Bay Area. (2/4)
More wind info from ECMWF Extreme Forecast Index 0.5 to 0.8 is an unusual pattern and >0.8 is very unusual. In other words on the extreme end. (3/4).
Read 4 tweets
This is the fire weather forecast I was hoping wouldn't come to pass, given all that has already transpired in 2020: Very strong offshore winds, coupled w/exceptionally low humidity & record-dry vegetation, will bring extremely critical wildfire risk Sun/Mon. 1/3 #CAwx #CAfire Image
This will likely be strongest & most widespread offshore wind event of season, & is reminiscent of extreme events in 2019 & 2017. Hardest-hit areas appear to be west slopes of Sierra Nevada (gusts of 70+mph) & SF Bay Area (widespread gusts 40-50mph; higher in hills). #CAwx Image
Exceptionally low atmospheric humidity (relative humidity of 5% or less and dewpoints below zero F) will accompany these strong winds. This will be a *cold* offshore wind event, and temperatures will drop precipitously (especially in mountains). #CAwx ImageImage
Read 4 tweets
New research led by @ggpersad & featuring @PabloWater. Using downscaled climate model simulations, we show that there is unexpectedly high inter-model agreement re: increasing extremity of California hydroclimate due to #ClimateChange. (1/n)… #CAwater
In general, climate models agree than an increasing fraction of California's overall precipitation will become concentrated into the most intense events--and that the most extreme precip events will themselves be substantially more intense. (2/n)… #CAwater
There is also agreement that CA's already pronounced precipitation seasonality will become even sharper--with more rain concentrated into winter months at expense of the autumn & spring. Consider the wildfire season implications... (3/n)… #CAwater #CAfire
Read 8 tweets
Fire weather update: relatively mild (near avg) temps will continue for a few more days across California. Calmer winds will result in poor air quality, as visible this AM. A weak cold front with a few light North Coast showers possible mid-week. But then... #CAwx #CAfire (1/n)
There is unfortunately multi-model ensemble agreement that a very strong ridge will build near CA and the West Coast by end of Sept., bringing yet another major heatwave by early October to CA, OR, and adjacent states. #CAwx #ORwx #CAfire (2/n)
Early indications is that this early Oct event will have potential to bring record heat to CA and possibly other areas. This will coincide with weak offshore flow, so should spread all the way to coast and bring extreme wildfire burning conditions once again. #CAwx #CAfire (3/n)
Read 4 tweets
I don’t think people are aware of how much of the west coast is burning right now: #WaWILDFIRE #OregonFires #CAfire…
While I have you, please take the time to confirm you’re registered to vote:
Read 5 tweets
Clear increase in daily total intensity of #CaliforniaFires & #ColoradoFires on 7 Sept >> 2003-2019 mean in #CopernicusAtmosphere GFAS data. Latest 24-hour aerosol & carbon monoxide forecasts show long-range transport of smoke extending across the US from SW to NE. ImageImageImageImage
Aerosol forecast charts ➡️…

Carbon monoxide forecast charts ➡️…
Incredible scale of ongoing #CaliforniaFires with total estimated #wildfire emissions for California to 7 Sept 2020 already state’s highest annual total in 18-year #CopernicusAtmosphere GFAS dataset (Colorado achieved this in August)… #CAfire #COfire ImageImage
Read 6 tweets
Finally some good news to report: last night's dry lightning event was less widespread & intense than earlier feared. Nearly all lightning spared Bay Area, though there were strikes in Central Valley & western Sierra foothills that may have sparked new fires. (1/3) #CAwx #CAfire Image
What happened? Well, there was *plenty* of elevated convection just above everywhere, but it wasn't *quite* deep enough to generate much lightning. Models were slightly off with timing, and may have underestimated smoke effect, and that made all the difference.#CAwx #CAFire (2/3)
Also: we still aren't totally out of the woods in NorCal. Dry thunderstorms are still expected today, mainly in northern 1/3 of state but possibly clipping North Bay. These could yet spark new fires. But all in all, a better than expected outcome. #CAwx #CAfire (3/3) Image
Read 3 tweets
A few thoughts (thread) on the upcoming lightning event in California. All models are showing the potential for at least isolated mixed wet/dry thunderstorms in central/northern California, which is obviously not good news given the number of fires already ongoing #CAwx #CAfire
The first wave (tonight-Sunday) appears a little weak and with the upper-level ridging in place, storms are going to be near the coast and track more offshore. But the second wave (Sunday night - Monday), breaks down the ridge and strong southerly develops over California #CAwx
Here is the NSSL-WRF forecast composite reflectivity (essentially what the radar may look like) for the next 48 hours. Chance of lightning tonight and Sunday afternoon. But stronger storms and more coverage Sunday night through Monday #CAwx
Read 10 tweets
Okay, time for a NorCal fire weather update. First, good news: fire activity decreased overnight due to development of shallow marine layer along immediate coast, and cooler temps inland. Next 24 hours, fire activity will be strongly diurnal (i.e.,like normal).#CAwx #CAfire (1/n) Image
The bad news: this is as good as things are going to get for a while. This wknd, ridge builds back in once again from east, suppressing marine layer and bringing hot/dry conditions inland (though will *not* be as hot as last record heatwave over past week). #CAwx #CAfire (2/n) Image
Then, slightly disconcerting news. Remnant moisture & instability from former Hurricane #Genevieve will approach CA from south on Sunday. Uncertainty remains, but right now it appears there is a real risk of *another* dry lightning event in NorCal Sun/Mon. #CAwx #CAfire (3/n) Image
Read 5 tweets
Absolutely incredible footage of #LoyaltonFire #pyrovortex ("Fire Tornado") earlier today. Pretty sure this validates @NWSReno's Tornado Warning--which is, I believe, the first ever issued by @NWS specifically for a wildfire-generated pyroconvective event. #CAwx #CAfire #NVwx
To be clear: this is *not* first documented instance of a large-scale fire vortex. Devastating #CarrFire in 2018 near Redding, CA produced one of the strongest such events in recent memory, outside of a couple of previous events during Australian firestorms. (1/3) #CAwx #CAfire
Such events are not a new phenomenon--they have probably occurred during particularly intense wildfires under the right atmospheric conditions since...well, time immemorial. But I suspect these recent events have been more noticeable for two key reasons: (2/3) #CAfire
Read 4 tweets
The upcoming California heatwave is looking increasingly impressive. Intense and long-duration event now expected except at the immediate coast. And this will be a relatively humid heatwave, with unusually warm overnight temps. Some record heat is possible. (1/3) #CAwx #CAfire
In addition to a strong ridge building in from SE, the remnant low pressure circulation from former #HurricaneElida will approach CA coast Thurs-Fri, bringing an unusually muggy summer airmass. This means heat will feel more uncomfortable than typical CA heatwave. (2/3) #CAwx
Beyond mugginess, this moisture surge will also bring
possibility of some elevated convective clouds, which could include some light showers or even isolated thunderstorms. Pretty skies, but something to keep an eye on from fire weather perspective. (3/3) #CAwx #CAfire
Read 3 tweets
New work led by @climate_guy & featuring @weathertrader, @pyrogeog, @tomwptak, & me on California fire weather & PG&E's "Public Safety Power Shut-offs!" We were motivated by widespread, prolonged, & disruptive events in 2019. (1/5)… #PSPS #CAwx #CAfire Image
We find 2019 fire wx conditions were indeed exceptional in decadal context. However, we were unable to replicate widespread extent of PG&E's actual PSPS outages using publicly-stated weather thresholds (big difference near SF Bay Area especially).… (2/5) Image
We find numerous pockets within PG&E service area subject to 2 or more PSPS events per year, even under typical conditions. Frequency & extent of PSPS risk zones highly sensitive to exact wind threshold used, w/high inter-annual variability.… (3/5) ImageImage
Read 5 tweets
Weather/climate programming note: (1/3)
Our extreme #climate event attribution piece will be out this Friday in @OneEarth_CP (expect a Tweetstorm, and brief discussion in an upcoming Weather West blog post!). #CAwx #CAwater
Then, in early July, our extreme California #AtmosphericRiver & #ClimateChange paper will be out in @ScienceAdvances (expect a dedicated Weather West blog post). #CAwx #CAwater (2/3)
In Aug/Sep, I'll have dedicated post discussing our recently published paper on #ClimateChange-caused increases in extreme CA wildfire conditions (& possibly also additional work, still in review, examining population exposure to public safety power shut-offs). #CAwx #CAfire(3/3)
Read 3 tweets
Very interesting weather set-up headed for NorCal this weekend. Heatwave breaks today near coast & tomorrow inland as cut-off low pressure system approaches coast. Then, late Fri into Sat, widespread elevated convection develops from SF Bay Area northward. (1/4) #CAwx #CAfire
This elevated convection will bring a good chance of thunderstorms, and the potential (at least initially) for some dry lightning--especially near I-80 corridor/Bay Area. Later storms on Saturday, and across far NorCal, will be wetter. #CAwx #CAfire (2/4) Image
In fact, models are now suggesting potential for locally heavy rainfall across far NorCal due to these widespread thunderstorms on Sat. This is an almost autumn-like convection pattern--storms will not be confined to usual spots, but will occur over valleys/coast too. #CAwx (3/4) Image
Read 4 tweets
Our new work on #ClimateChange & autumn wildfire risk in California, led by Michael Goss, is out today in (open-access) ERL. We find that climate change has already doubled the frequency of extreme fire weather days since 1980s.(1/6) #CAwx #CAfire #CAwater… Image
Historical increases in autumn temperature & decreases in precipitation have led to increased number of days where aggregate Fire Weather Index (FWI) exceeds historical 95th percentile, which are strongly associated w/large wildfires.(2/6) #CAfire #CAwx… ImageImage
This historically observed increase in autumn wildfire risk in California is generally consistent with climate model projections for the same period. #CAwx #CAfire (3/6)… Image
Read 7 tweets
Light coastal rain showers (and mountain snow showers) are still expected to end prolonged dry spell in NorCal this weekend (finally!), although significant precip not expected. Then, early next week... 1/3 #CAwx #CAwater Image
Early next week, a stronger & dramatically warmer system is expected to affect SoCal. Widespread, locally heavy rainfall is likely from this warm/wet #AtmosphericRiver--but only in far SoCal. Very high snow levels due to subtropical airmass. 2/3 #CAwx #CAwater Image
Thereafter, there is uncertainty regarding how the pattern evolves. Best chance of additional precip is in SoCal; unfortunately, in parched NorCal, ensembles still suggesting continued below-average precip through mid-March. #CAwx #CAwater #CAfire Image
Read 3 tweets
More record high temperatures possible over the next few days across California. With ensembles projecting zero precipitation in San Francisco and Sacramento through Saturday evening, February 2020 now virtually certain to be driest in history across most of NorCal. #CAwx ImageImage
Models now suggesting Sunday system may be an "outside slider"--missing most of CA to the west and possibly leaving NorCal dry, cool, and windy. Scattered SoCal rain showers and Sierra Nevada snow showers still possible. #CAwx
Still some hints of the possibility of a wetter pattern by mid-March, but ensembles are mixed on this and would likely not occur until 2nd week in month or later. Based on current forecasts, I would not hold my breath for a "March Miracle" this year.... #CAwx #CAfire #CAwater ImageImage
Read 4 tweets
No sign of widespread/significant precipitation anywhere in California over the next 2+ weeks. Already large seasonal precip deficits will continue to grow, esp. across Norcal, as very strong and persistent northeastern Pacific ridge builds. #CAwx
In fact, much of the Northern Hemisphere mid-latitudes will experience anomalous ridging in the coming days. This hemispheric atmospheric mass displacement is a reflection of the presently record-strong positive phase of the Arctic Oscillation...
As @RobMayeda pointed out, this already prolonged dry spell is already leading to low soil moisture and dry vegetation at what is typically wettest time of year in California. #CAwx #CAfire
Read 4 tweets
Complex and honestly pretty bizarre weather pattern shaping up for California over next 10+ days. First, widespread record heat possible this weekend/early next week. Temperatures into 80s and even 90s in some spots. #CAwx #CAfire (1/3)
Then, a slow-moving cut-off low will likely bring some showers & thunderstorms to parts of SoCal, including coast, and *eastern* slopes of Sierra Nevada. Still some model disagreement, but precip could range from trivial (GFS) to significant (ECMWF) there. #CAwx #CAfire(2/3)
Meanwhile, northern 2/3 of CA will stay dry despite this system to the south. Strong pressure gradients on north side of the low could drive strong northerly winds, possibly leading to another round of extreme fire weather concerns given record-dry vegetation. #CAwx #CAfire (3/3)
Read 3 tweets
1/n: Wildfire Gratitude: W/ fire activity moderating, I want to thank some folks. 1st firefighters on front lines who let me photograph their work to save lives+property. Seeing you bust your tails day after day up close gives me continued respect for the yeoman’s work you do.
2/n: To law enforcement. I can get on your case in the heat of things when some try and deny 409.5/media access, but the majority are professional, courteous, and often lack the PPE or safety gear, but are still keeping the peace during major fires. Thank you.
3/n: To OES, logistics, support, camp crews, utility+road road workers, and dispatchers supporting frontline first responders. You keep the machine humming and well-oiled. None of this would happen without you!
Read 11 tweets
1/4 Why is perimeter data on the #Inciweb fire map out-of-date? The Inciweb map simply displays perimeter data that is hosted on the GeoMAC #GIS server. Why doesn’t the GeoMAC server have current perimeter data? #WAfire #ORfire #CAfire #AZfire #COfire #MTfire #GeoSpatial
2/4 For most big fires there usually is a nighttime overflight with infrared sensing gear. Experts analyze that data and determine a new fire perimeter. They also determine areas of intense, scattered and isolated heat. That data is then hosted on the public NIFC FTP server.
3/4 That new fire perimeter eventually shows up on the GeoMAC server and will then appear on the Inciweb map. The problem is that it seems to take a day or more for that perimeter data to go from the NIFC server to the GeoMAC server. Surely that process could be speeded up.
Read 4 tweets
Thread inspired by yesterday's truly spectacular and widely discussed Great Plains-style supercell in California's Sacramento Valley. #CAwx #Redding #ShastaCounty (1/n)
Thunderstorms in general are much less common along the West Coast of North America than across nearly all other parts of the continent. Some parts of coastal California see one (or even fewer!) thunderstorms in a typical year. #CAwx (2/n)
Cumulonimbus clouds associated w/t-storms require strong upward vertical motion in order to form. Sometimes, this can be generated by boundary, like a cold front; other times, mere heating of humid lower atm can be sufficient for air to spontaneously rise, cool, &condense.(3/n)
Read 13 tweets

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